A two-stroke engine of this kind is disclosed in German Patent 3,222,457. The cylinder housing includes a cylinder having a crankcase half which is formed as one piece on the foot of the cylinder. The crankcase half is closed with a crankcase cover secured with threaded fasteners. On mutually opposite sides of the crankcase, a crankshaft is journalled in shaft bearings and, for this purpose, half shells are formed in the cylinder housing and the crankcase cover. The half shells formed in the cylinder housing for accommodating the shaft bearing are interrupted with respect to their supporting surfaces by overflow channels which lead from the crankcase into the combustion chamber and are open at their ends toward the crankcase cover. The interrupted supporting surface of the half shell in the cylinder housing can lead to an inadequate support of the shaft bearing so that the shaft bearing tends to deform ovally under load causing bearing wear to be very substantial. The half shells support the shaft bearing.
More critical exhaust-gas requirements mandate an optimization of the purging and the charging of the combustion chamber and, for this purpose, the number of overflow channels is increased. Because of the increased number of overflow channels, the support surface of the half shell accommodating the shaft bearing in the cylinder housing is further reduced. In order to still ensure an adequate support of the shaft bearing, the diameter and therefore the diameter of the half shell is increased. This not only leads to increased weight but to an overall increased structural size because the crankcase cover must be configured larger in order to take the larger shaft bearing into account. In addition, larger shaft bearings have a lower maximum permissible rpm and this leads to problems at the high rpms of the two-stroke engines used in portable handheld work apparatus.